Various systems are known to stretch a plate, such as a printing plate, on the form cylinder of a rotary printing machine, see for example German Patent DE 33 39 185; in this arrangement, the form cylinder has an axially extending cylinder groove cut therein, symmetrical with respect to a leading or trailing side, in which a clamping or stretching spindle is rotatably located. The spindle can rotate about its axis, and the groove is formed with an external slit so that the ends of the printing plate can be introduced through the slit, to be then clamped therein. One of the walls of the groove is formed with a support element, adapted to bear against the clamping spindle, in order to counteract bendthrough of the spindle. Since form cylinders of such printing machines can operate in clockwise (CW) or counterclockwise (CCW) direction, the spindle support element is located, in accordance with the then used direction of rotation, at the right or at the left side of the clamping groove wall.
The spindle support element is secured to the wall of the groove, for example by an adhesive, or is otherwise attached thereto. Consequently, when the direction of rotation of the form cylinder is to be reversed, it is necessary to remove the form cylinder, and replace it with one in which the support element is at the other side of the groove wall. The fixed attachment of the spindle support is necessary to prevent unintended loosening of the support, which might fall out of the groove, and damage the printing machine. Simple reversal of rotation of the form cylinder, thus, is not possible in machines of this type.